Function highlight

src/textual/highlight.py:184–238

Apply syntax highlighting to a string. Args: code: A string to highlight. language: The language to highlight. theme: A HighlightTheme class (type not instance). tab_size: Number of spaces in a tab. Returns: A Content instance which may be used in a

(
    code: str,
    *,
    language: str | None = None,
    path: str | None = None,
    theme: type[HighlightTheme] = HighlightTheme,
    tab_size: int = 8,
)

def highlight(
    code: str,
    *,
    language: str | None = None,
    path: str | None = None,
    theme: type[HighlightTheme] = HighlightTheme,
    tab_size: int = 8,
) -> Content:
    """Apply syntax highlighting to a string.

    Args:
        code: A string to highlight.
        language: The language to highlight.
        theme: A HighlightTheme class (type not instance).
        tab_size: Number of spaces in a tab.

    Returns:
        A Content instance which may be used in a widget.
    """
    if not language:
        language = guess_language(code, path)

    assert language is not None
    code = "\n".join(code.splitlines())
    try:
        lexer = get_lexer_by_name(
            language,
            stripnl=False,
            ensurenl=True,
            tabsize=tab_size,
        )
    except ClassNotFound:
        lexer = get_lexer_by_name(
            "text",
            stripnl=False,
            ensurenl=True,
            tabsize=tab_size,
        )

    token_start = 0
    spans: list[Span] = []
    styles = theme.STYLES

    for token_type, token in lexer.get_tokens(code):
        token_end = token_start + len(token)
        while True:
            if style := styles.get(token_type):
                spans.append(Span(token_start, token_end, style))
                break
            if (token_type := token_type.parent) is None:
                break
        token_start = token_end

    highlighted_code = Content(code, spans=spans).stylize_before("$text")
    return highlighted_code